module c

import v.ast

pub struct ProfileCounterMeta {
    fn_name   string
    vpc_name  string
    vpc_calls string
}

fn (mut g Gen) profile_fn(fn_decl ast.FnDecl) {
    if g.pref.profile_no_inline && fn_decl.attrs.contains('inline') {
        g.defer_profile_code = ''
        return
    }
    fn_name := fn_decl.name
    cfn_name := g.last_fn_c_name
    if fn_name.starts_with('time.vpc_now') || fn_name.starts_with('v.profile.') {
        g.defer_profile_code = ''
    } else {
        measure_fn_name := if g.pref.os == .macos { 'time__vpc_now_darwin' } else { 'time__vpc_now' }
        // Prefix the counter names with a unique per-function index. Without it the derived
        // names collide: a function `…__lower`'s call counter is `vpc_…__lower_calls` (u64),
        // which is identical to a function `…__lower_calls`'s time accumulator `vpc_…__lower_calls`
        // (double) — a "redefinition with a different type" C error. The same holds for the
        // `_only_current` suffix. The index makes every base name unambiguous.
        fn_profile_counter_name := 'vpc_${g.pcs.len}_${cfn_name}'
        fn_profile_counter_name_calls := '${fn_profile_counter_name}_calls'
        g.writeln('')
        should_restore_v__profile_enabled := g.pref.profile_fns.len > 0
            && cfn_name in g.pref.profile_fns
        if should_restore_v__profile_enabled {
            $if trace_profile_fns ? {
                eprintln('> profile_fn | ${g.pref.profile_fns} | ${cfn_name}')
            }
            g.writeln('\tbool _prev_v__profile_enabled = v__profile_enabled;')
            g.writeln('\tv__profile_enabled = true;')
        }
        g.writeln('\tdouble _PROF_FN_START = ${measure_fn_name}();')
        g.writeln('\tdouble _PROF_PREV_MEASURED_TIME = prof_measured_time;')
        g.writeln('if(v__profile_enabled) { ${fn_profile_counter_name_calls}++; } // ${fn_name}')
        g.writeln('')
        g.defer_profile_code = '\tif(v__profile_enabled) { \n\t\tdouble _PROF_ELAPSED = ${measure_fn_name}() - _PROF_FN_START;\n'
        g.defer_profile_code += '\t\t${fn_profile_counter_name} += _PROF_ELAPSED;\n'
        g.defer_profile_code += '\t\t${fn_profile_counter_name}_only_current += _PROF_ELAPSED - (prof_measured_time - _PROF_PREV_MEASURED_TIME);\n'
        g.defer_profile_code += '\t\tprof_measured_time = _PROF_PREV_MEASURED_TIME + _PROF_ELAPSED;\n\t}'
        if should_restore_v__profile_enabled {
            g.defer_profile_code += '\n\t\tv__profile_enabled = _prev_v__profile_enabled;'
        }
        g.pcs_declarations.writeln('double ${fn_profile_counter_name} = 0.0; double ${fn_profile_counter_name}_only_current = 0.0; u64 ${fn_profile_counter_name_calls} = 0;')
        g.pcs << ProfileCounterMeta{
            fn_name:   cfn_name
            vpc_name:  fn_profile_counter_name
            vpc_calls: fn_profile_counter_name_calls
        }
    }
}

pub fn (mut g Gen) gen_vprint_profile_stats() {
    g.pcs_declarations.writeln('void vprint_profile_stats(){')
    fstring := '"%14llu %14.3fms %14.3fms %14.0fns %s \\n"'
    g.pcs_declarations.writeln('\tf64 f = 1.0;')
    if g.pref.os == .windows {
        // QueryPerformanceCounter() / QueryPerformanceFrequency()
        // https://learn.microsoft.com/en-us/windows/win32/sysinfo/acquiring-high-resolution-time-stamps
        g.pcs_declarations.writeln('\tu64 freq_time = 0;')
        g.pcs_declarations.writeln('\tQueryPerformanceFrequency(((voidptr)(&freq_time)));')
        g.pcs_declarations.writeln('\tf = (f64)1000000000.0/(f64)freq_time;')
    }
    if g.pref.profile_file == '-' {
        for pc_meta in g.pcs {
            g.pcs_declarations.writeln('\tif (${pc_meta.vpc_calls}) printf(${fstring}, ${pc_meta.vpc_calls}, (${pc_meta.vpc_name}*f)/1000000.0, (${pc_meta.vpc_name}_only_current*f)/1000000.0, (${pc_meta.vpc_name}*f)/${pc_meta.vpc_calls}, "${pc_meta.fn_name}" );')
        }
    } else {
        g.pcs_declarations.writeln('\tFILE * fp;')
        g.pcs_declarations.writeln('\tfp = fopen ("${g.pref.profile_file}", "w+");')
        for pc_meta in g.pcs {
            g.pcs_declarations.writeln('\tif (${pc_meta.vpc_calls}) fprintf(fp, ${fstring}, ${pc_meta.vpc_calls}, (${pc_meta.vpc_name}*f)/1000000.0, (${pc_meta.vpc_name}_only_current*f)/1000000.0, (${pc_meta.vpc_name}*f)/${pc_meta.vpc_calls}, "${pc_meta.fn_name}" );')
        }
        g.pcs_declarations.writeln('\tfclose(fp);')
    }
    g.pcs_declarations.writeln('}')
    g.pcs_declarations.writeln('')
    g.pcs_declarations.writeln('void vreset_profile_stats(){')
    for pc_meta in g.pcs {
        g.pcs_declarations.writeln('\t${pc_meta.vpc_calls} = 0;')
        g.pcs_declarations.writeln('\t${pc_meta.vpc_name} = 0.0;')
    }
    g.pcs_declarations.writeln('}')
    g.pcs_declarations.writeln('')

    g.pcs_declarations.writeln('void vprint_profile_stats_on_signal(int sig){')
    g.pcs_declarations.writeln('\texit(130);')
    g.pcs_declarations.writeln('}')
    g.pcs_declarations.writeln('')
}